The present invention relates to a supporting air cushion shoe able to support a load movable on a substantially flat guide surface with low friction.
Air cushion shoes are known comprising a flat surface able to cooperate with the said guide surface, and means for introduction and distribution of compressed air between the said surfaces in such a way as to produce a supporting fluid cushion between the surfaces themselves. Such shoes find application predominantly on high precision systems (for example, measurement machines, positioning systems etc) in which the presence of friction between the parts in relative movement is detrimental to the precision and dynamics. Systems of the type described generally require the presence of stop means between the parts in relative movement in that the simple interruption of the supply of compressed air to the shoes is not sufficient to obtain a stable, immediate and precise positioning between the said parts.
Such stop means, of mechanical or electromagnetic nature, are usually made as a unit separate from the supporting shoes. This involves a relatively large encumbrance due to the dimensions of the supporting shoes themselves and of the stop unit; moreover, this involves the necessity of utilising more shoes and/or more stop units for the purpose of obtaining two force systems (supporting and stop forces respectively) with the respective resultants having a common line of action; this condition is, in fact, necessary so that the system will be subject to a pure force (supporting or stopping force depending on the predominance of one of the two resultants) acting on a plane orthogonal to the cooperating flat surfaces, without disturbing couples.